ABSTRACT
Objective:To investigate the effect of mid-ventricular obstruction (MVO) on left ventricular systolic function in patients with hypertrophic cardiomyopathy(HCM) by four-dimensional automatic left ventricular quantitation technology(4D Auto LVQ).Methods:Fifty-seven hypertrophic obstructive cardiomyopathy patients were selected from December 2020 to October 2022 in the First Affiliated Hospital of Zhengzhou University. According to the presence of MVO, HCM patients were divided into two groups: HCM 1 group, HCM without MVO ( n=34); HCM 2 group, HCM with MVO ( n=23). In addition, 25 healthy subjects in the same period were selected as the control group. Conventional ultrasound parameters were collected, and 4D Auto LVQ technology was used to obtain the mechanical parameters of left ventricular myocardium, including left ventricular longitudinal strain (GLS), circumferential strain (GCS), area strain (GAS), radial strain (GRS), segmental longitudinal strain (SLS) and area strain (SAS). The differences of these parameters among the three groups were compared. Results:①Compared with the control group, the thickness of the maximum basal segment of interventricular septum, the thickness of the middle segment of the maximum interventricular septum, the thickness of the apical segment of the interventricular septum, the thickness of the left ventricular posterior wall and left atrium diameter were significantly increased. Six-minute walk distance and the left ventricular end-diastolic diameter was decreased in the two groups of HCM(all P<0.05). Left ventricular outflow tract gradients in HCM 1 group was higher than HCM 2 group( P<0.05), but there was no significant difference in left ventricular ejection fraction among the three groups( P>0.05). There was significant difference in the incidence of left ventricular apical aneurysm among the three groups( P<0.05). ②Compared with the control group, the GLS in both HCM groups was lower, and it was lower in the HCM 2 group than in the HCM 1 group(all P<0.05) the GRS and GAS in both HCM groups were lower than in the control group ( P<0.05), and there was no significant difference between the two groups of HCM, and there was no significant difference in GCS among the three groups(all P>0.05). ③Compared with the control group, the SLS of basal segment, middle segment, apical cap, posterior septum, inferior wall and lateral wall in HCM group were significantly lower than those in control group. The SLS of apical segment of posterior septum, anterior septum, anterior wall, posterior wall, inferior wall and apical segment of posterior septum, lateral wall and inferior wall in HCM 2 group were significantly lower than HCM 1 group(all P<0.05), but there was no significant difference in SLS of posterior septum, anterior septum, anterior wall, lateral wall and inferior wall between the two groups(all P>0.05). ④Compared with the control group, the SAS of posterior septal basal segment, middle segment, anterior septal middle segment, anterior wall basal segment, middle segment, apical segment, lateral wall basal segment, middle segment, apical segment, posterior wall basal segment, middle segment, inferior wall basal segment, middle segment and apical cap in HCM groups were significantly lower than the control group(all P<0.05), but there was no significant difference in SAS between the two groups of HCM( P>0.05). Conclusions:4D Auto LVQ can quantitatively evaluate the damage of MVO on the left ventricular systolic function in patients with HCM, especially for the evaluation of local myocardial function damage in the medial segment and apical segment.
ABSTRACT
BACKGROUND: Mid-ventricular obstruction(MVO) of the left ventricle has been reported to be associated with mid-ventricular hypertrophy, papillary muscle hypertrophy, severe apical hypertrophy, elderly hypertension, and dobutamine stress echocardiography(DSE). The aim of this study is to determine the clinical and echocardiographic features of MVO. METHOD: MVO was defined as systolic hourglass narrowing of the left mid-ventricle in the apical long axis view with turbulent flow exceeding 1m/s. Fifteen patients were suvjected to this retrospective analysis. Baseline patients characteristics were mean age 56(range, 26-74)years, male gender 10(66%). Associated diseases were hypertrophic cardiomyopathy 9, aortic stenosis 1, hypertension without left ventricular hypertrophy(LVH) 1, old myocardial infarction with apical aneurysm 2, stable angina 1, and idiopathic 1. DSE was performed in 7 of 15 subjected patients to evaluate the chest pain. RESULTS: All patients had mild symptoms; chest tightness, palpitation, and weakness, without syncope nor hypotension. MVO was observed in 10 at rest, and 5 after provocation ; DSE 3, VPB 1, atropine 1. Observed peak velocity in the mid-ventricle ranged from 1.2 to 5.5m/s(mean ; 2.8±1.6m/s). Left ventricular outflow tract obstruction defined as the peak flow velocity exceeded 1.5m/s, was also present in 8. in 7 underwent to DSE, systolic blood pressure was changed from 144±15mmHg at rest to 175±28mmHg at peak, heart rate from 73±12/min to 108±23/min, left ventricular end diastolic dimension from 42±5mm to 37±4mm, ejection fraction from 66±10% to 80±6%, and peak flow velocity at the mid-ventricle from 1.0±0.6m/s to 3.3±1.7m/s. CONCLUSION: MVO can be observed in patients without LVH and may account for clinical symptoms of chest discomfort. The mechanism of MVO, at least in part, and be explained with increased ventricular contractility, increased heart rate, and small left ventricular cavity size.